Figure 7.

Co-infection Leads to Elevated Levels of Plasma Heme and Favors Bacterial Persistence Dependent on Uptake of Extracellular Iron

(A) C57BL/6 mice were infected with P. chabaudi-RBCs and/or with C. rodentium. (A) Heme levels were measured in plasma samples collected between 9 and 14 days post-infection. Data represent pooled results from two independent experiments (n = 3–9 mice/group/time point). Each symbol represents an individual mouse and bars denote group means. Statistical significance was determined by the Mann-Whitney test. ^∗∗p < 0.01 and ^∗∗∗∗p < 0.0001.

(B) Spleen cells were collected between 9 and 14 dpi, and mitochondrial ROS was assessed in CD11b⁺ cells by measuring MitoSox by flow cytometry after culture with medium or PMA. Data shown are representative of one experiment (n = 4–14 mice per group). Each symbol represents an individual mouse and bars denote group means. Statistical significance was determined by the Mann-Whitney test (^∗p < 0.05).

(C and D) Additional cohorts of uninfected or C. rodentium-infected C57BL/6 mice received hemin intraperitoneally (50 μmol kg/body weight per dose) once per day, starting at 3 dpi until 11 dpi and then body weight and survival were monitored. Symbols represent mean ± SEM as a percentage of the initial body weight. Data shown are representative of two independent experiments (n = 4–10 mice per group).

(E and F) Additional cohorts of C57BL/6 mice were infected orally with 1 × 10⁹ CFU of the isogenic C. rodentium fepA mutant strain or with its control strain DBS120 C. rodentium or co-infected with these strains and P. chabaudi at day 0. Body weights and survival were monitored. Symbols represent mean ± SEM as a percentage of the initial body weight. Data shown were pooled from two independent experiments (n = 10–33 mice/group).